Andrew Hicks has been so bold as to add a new book about world harmony, the music of the spheres, and the medieval reception of the Pythagorean concept of a creation organised according to musical principles to the already existing wealth of scholarship. Is there room to shed yet new light on this old and often visited theme, however much it captures the imagination? The answer to this question is clear: yes, there is. Hicks has chosen an approach which is new and refreshing, and which goes far beyond the boundaries of what already exists on the subject. So far, pertinent books and articles have often been geared towards interests either in the field of musicology or in philosophy, but in this book these fields are truly merged. Moreover, he explores texts from a period in which the theme is generally understood to have retreated to the background: the twelfth century. For this was the century in which the newly translated Aristotelian texts on natural philosophy were taken up in the curriculum, and caused a shift in the understanding of the harmony of the cosmos: no longer were the heavens believed to bring forth actual perfect music, but rather to mirror the perfect ratios of the act of creation in the abstract. The music of the cosmos was supposed to have been silenced. Musical treatises from this century no longer seem to be interested in rooting their discipline in the quadrivial, Platonic and Pythagorean ground. Speculative music theory as we know it from ancient, late antique and early medieval texts seems to have been left behind and traded for the codification of contemporary music practice, with its fast developing polyphony. In this book, Hicks convincingly shows that the theme does not disappear: it remains an important argument in theories about the cosmos, the senses and the human understanding of God and man's (in)ability to grasp the essence of things.

In the prelude, ‘Listening to the Universe’, Hicks sketches the starting-point of the book: the recent observation of gravitational waves in the universe has made physicists exclaim that we are now able to hear the music of the cosmos, the sounds of space-time. To find the roots of this claim, or, if we prefer, this allegory of a harmonious, sonorous, rationally organised and therefore understandable and comprehensible cosmos, he takes us back to the ancient and medieval roots of it in the Latin West. There are still many gaps to fill in our knowledge of the music of the cosmos, Hicks explains, especially for the twelfth century. His focus is on twelfth-century cosmologists, interested in nature and natural processes in response to and in dialogue with their Platonic texts: Calcidius's translation and commentary on Plato's Timaeus, Macrobius's Commentary on the Dream of Scipio, Martianus Capella's Marriage of Mercury and Philology and Boethius's treatises on Arithmetic, Music and his Consolation of Philosophy. These texts, Hicks shows, were studied and contemplated together; the twelfth-century scholars were clearly out to find their shared concepts and ideas, their correspondences and differences. Their syntheses of Plato, Calcidius, Macrobius and Boethius are tools to explore the full range of the ars musica: its philosophical, speculative, natural philosophical and metaphysical aspects and how these aspects can be used to understand the world, man and God.

Two parts follow this prelude. Part I is called ‘The Framework’ and sketches the medieval reality of the disciplines in which the theme of the harmonious cosmos plays a role: natural philosophy on the one hand, and the disciplines of music, mathematics and physics on the other. In Part II, ‘The Particulars’, Hicks brings material together on three sub-themes: the harmony of the human body (microcosmos), the harmony of nature, and the harmony of the cosmos (macrocosmos). In a postlude he draws all these threads together and discusses the role of aesthetics as a driving principle in medieval systems of knowledge and understanding. In two appendices, previously unpublished texts are presented: William of Conches, Glosulae de magno Prisciano and Hisdosus, De anima mundi platonica. A good bibliography and index complete the book.Footnote ¹

As a specialist on Carolingian intellectual history, I cannot comment in depth on many of the detailed descriptions and analyses of the philosophical texts treated in this book. Specialists on the twelfth-century School of Chartres (associated with the famous thinkers Gilbert of Poitiers, William of Conches, Thierry of Chartres and John of Salisbury), on twelfth-century Aristotelianism and Abelard would be, in fact, much better suited as reviewers than I am. Still, I would like to treat some specific points to show how and why the book matters in my view. In Part I, Hicks first picks apart the long history of a cosmos organised according to divine principles, starting with Boethius, who was the main hinge between ancient and medieval learning on the subject. A notion that is new to the twelfth century, however, is the division between creator and creation, between (crudely put) the main subject of theology and that of natural philosophy. By arguing that creation is not its creator but just a manifestation of some aspect of its power, and by introducing multiple divisions of the concept of ‘nature’, the twelfth-century philosophers showed that human knowledge of the creation is something that is achievable. Nature is something that can be observed and explained, and it is useful to do so. Moreover, music, as the liberal art which embraces both a mathematically founded science and a metaphysical musica speculativa, played a crucial role. Hicks shows how divisions of knowledge underscore this ontological and epistemological standpoint, giving mathematics, the theoretical disciplines and, of course, music their rightful place in knowledge diagrams.

In Part II, ‘The Particulars’, Hicks addresses three sub-topics, the first being the harmony of the human body and its soul. The addition of the soul as separate from the body in this analysis strikes me as new and exciting: Hicks uses it to guide the reader along a string of unexpected texts and pick up on their concepts and theories. The second concentrates on ‘hearing the world’, and leads again to an unexpected source for comments and thoughts: Priscian's grammatical treatise, which opens with philosophical ideas about vox, sound and animus. The introduction of these concepts at the opening of a grammar book led to philosophical accounts of what sound is, how the human voice is animated air and how hearing actually works. The paradigms of vox and hearing are picked apart in this chapter, illustrated again by numerous texts from commentaries (mainly on Priscian and Boethius), but also in newly composed quaestiones and treatises composed by such figures as Abelard and Adelard of Bath, reflecting the newly translated Aristotelian texts that shaped their learned background. In the third part, the usual suspect is finally addressed: the harmony of the spheres. It is well known that in the twelfth century, the idea of a sounding cosmos was eclipsed by one that did not produce actual music, but rather reflected a symbolic, anagogical mirror of a harmoniously composed world. Yet Hicks points out that this gradual shift does not mean the end of the music of the spheres, but rather a new kind of understanding on a different level: an ‘absorption into a more generic concept of nature’ (p. 192). The argument is built up from its Platonic roots, through the Latin late antique interpretations and into the twelfth-century discussions of the World Soul. The spread of a diagram (figs. 5.1 and 5.2) that visualises the connections between Calcidius, Macrobius and Boethius shows both the continuity of the knowledge tradition and the new ways in which it functioned in the learned tradition of the period.

With this diagram and the discussion of a second, planetary diagram, Hicks introduces a new strategy in his analysis: whereas up to this point the whole discussion was mainly based on a close reading of texts, which he stringed together to make a meaningful narrative, here, for the first time, the material aspect of the texts he studies comes into play. While I applaud the initiative, I wonder whether this aspect could not have offered even more insights. Throughout the book, we learn a lot about the texts themselves, their content, their inter- and intratextuality, their meaning and interpretation, but very little about their historical existence: how often were they copied and how were their manuscripts spread over Europe? Do the physical characteristics of their copies reveal anything about their intended audience? In this sense, Hicks shows himself very much a philologist, but not a particularly well-developed New Philologist. This, however, is not a criticism, but rather a curiosity. I wonder how these extra angles and questions would either strengthen or moderate Hicks's conclusions.

To conclude: this book is not fit for the faint-hearted who shy away from hard-core medieval philosophy.Footnote ² It is no easy introduction into the history of a widely loved theme. It is hard work, but very rewarding: new texts are opened up and new, unexpected and important connections are made, not only from the ancient to the medieval tradition, but also to the early modern and modern world of science, music and the science of music.